The preparation of novel poly (ether imide), PEI, microporous membranes with dormant surface sites for functionalization via surface initiated atom transfer radical polymerization (ATRP), was illustrated. Electrophilic substitutions of the aromatic rings have been reported in the main chain of polyimides (PI) by chloromethylation. The structure and composition of PEI before and after chloromethylation were studied by H NMR spectroscopy. The chemical composition of the membrane surfaces at various stages of surface modification was determined by X-ray photoelectron spectroscopy (XPS).